Penetration depth limits of in vivo confocal reflectance imaging.

We present experiments to predict the maximum penetration depth atwhich typical biological structures in amelanotic tissue can bedetected with confocal microscopy. The detected signal is examinedas the signal source strength (index of refraction mismatch), thesource depth, and the medium scattering coefficient are varied. Thedetected background produced by scattering outside the focal volume isexamined as the medium scattering coefficient, the depth in the medium, the dimensionless pinhole radius, nu(p), and theshape of the scattering phase function are varied.

Near real time confocal microscopy of cultured amelanotic cells: sources of signal, contrast agents and limits of contrast.

The use of high resolution, in vivo confocal imaging for noninvasive assessment of tissue pathology may offer a clinically important adjunct to standard histopathological techniques. To augment the present understanding of both the capabilities and limitations of in vivo confocal imaging, we investigated cellular sources of image contrast in amelanotic tissues, how contrast can be enhanced with external agents and how contrast is degraded by the scattering of overlying cells. A high-resolution reflected light confocal microscope was constructed and used to obtain images of various types of unstained amelanotic cells in suspension in real time before and after the addition of contrast agents.

Sources of contrast in confocal reflectance imaging.

The relationship between optical properties and image contrast in confocal imaging is investigated. A Monte Carlo simulation has been developed to analyze the effects of changes in scattering, index of refraction, and absorption in a three-layer medium. Contrast was calculated from the computed signal-to-background ratios for changes in tissue optical properties.

Corneal photocoagulation with continuous wave and pulsed holmium: YAG radiation.

In this study, the effectiveness of pulsed and continuous wave (CW) holmium: YAG lasers in coagulating in vitro pig corneas was analyzed. With the CW laser, irradiance and exposure time were varied; irradiance, from 162 to 324 W/cm2 and exposure time, from 200 to 800 ms. With the pulsed laser, number of pulses and radiant exposure were varied; number of pulses per lesion, from 4 to 30 and radiant exposure, from 10 to 25 J/cm2.